Nokea
Koch apparatus uses temperature of:
- A. 90°C
- B. 95°C
- C. 100°C
- D. 110°C
Correct Answer: C
Rationale: The correct answer is C (100°C) because the Koch apparatus is used for sterilization, and the standard temperature for sterilization is 100°C. At this temperature, most microorganisms are killed, making it an effective method for sterilization. Choice A (90°C), B (95°C), and D (110°C) are incorrect because they are not commonly used temperatures for sterilization purposes. Choosing a temperature lower than 100°C may not effectively kill all microorganisms, while choosing a temperature higher than 100°C may lead to unnecessary energy consumption without providing additional sterilization benefits.
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Which of the following bacteria is capable of surviving in extreme heat?
- A. Escherichia coli
- B. Bacillus subtilis
- C. Staphylococcus aureus
- D. Clostridium botulinum
Correct Answer: B
Rationale: The correct answer is B: Bacillus subtilis. Bacillus subtilis is a thermophilic bacterium capable of surviving in extreme heat due to its heat-resistant spores. It forms spores when exposed to unfavorable conditions, allowing it to withstand high temperatures. Escherichia coli (A), Staphylococcus aureus (C), and Clostridium botulinum (D) are mesophilic bacteria that do not have the same heat resistance mechanisms as Bacillus subtilis, making them unable to survive in extreme heat conditions.
Which of the following bacteria are capable of forming spores?
- A. Staphylococcus aureus
- B. Clostridium botulinum
- C. Escherichia coli
- D. Neisseria gonorrhoeae
Correct Answer: B
Rationale: The correct answer is B, Clostridium botulinum. This bacterium is capable of forming spores, which are dormant, resistant structures that help bacteria survive harsh conditions. Staphylococcus aureus (A), Escherichia coli (C), and Neisseria gonorrhoeae (D) do not form spores. Staphylococcus aureus is a gram-positive bacterium that does not produce spores. Escherichia coli is a gram-negative bacterium that also does not form spores. Neisseria gonorrhoeae is a gram-negative bacterium and does not have the ability to form spores. Therefore, the only bacteria among the options that can form spores is Clostridium botulinum.
Which of the following bacteria is associated with the formation of dental caries?
- A. Streptococcus mutans
- B. Streptococcus pneumoniae
- C. Bacillus cereus
- D. Clostridium tetani
Correct Answer: A
Rationale: Step 1: Streptococcus mutans is known for its ability to produce lactic acid, which contributes to the demineralization of tooth enamel, leading to dental caries.
Step 2: Streptococcus pneumoniae is a common respiratory pathogen and not directly associated with dental caries.
Step 3: Bacillus cereus is a foodborne pathogen and not typically found in the oral cavity or associated with dental caries.
Step 4: Clostridium tetani causes tetanus, a neurological condition, and is not involved in the formation of dental caries.
Summary: Choice A is correct as Streptococcus mutans is specifically linked to dental caries due to its acidogenic and aciduric properties. Choices B, C, and D are incorrect as they are not associated with dental caries.
Which bacteria are known for their ability to survive in extreme heat?
- A. Psychrophiles
- B. Mesophiles
- C. Thermophiles
- D. Halophiles
Correct Answer: C
Rationale: The correct answer is C: Thermophiles. Thermophiles are bacteria that thrive in high temperatures typically above 45°C. They have specialized enzymes and cellular structures that allow them to survive and even thrive in extreme heat. Psychrophiles (A) are adapted to cold temperatures, mesophiles (B) thrive at moderate temperatures, and halophiles (D) prefer high salt concentrations, making them unsuitable for extreme heat survival. Therefore, Thermophiles are the only bacteria among the choices that are known for their ability to survive in extreme heat.
Bacterioscopic examination of chancre material revealed some mobile, long, convoluted microorganisms with 8-12 regular coils. These features are typical for:
- A. Treponema
- B. Borrellia
- C. Leptospira
- D. Vibrios
Correct Answer: A
Rationale: The correct answer is A: Treponema. Treponema pallidum is a spirochete bacterium that appears as long, thin, and spiral-shaped microorganisms with 8-12 regular coils under the microscope. This characteristic morphology is specific to Treponema species, making it the correct choice. Borrelia, Leptospira, and Vibrios have different shapes and arrangements under the microscope, making them incorrect choices in this scenario.